This project builds on previous research that documented the potential for utilizing rice straw as a livestock forage supplement.  Defining field practices that can improve forage quality and testing baled straw will help improve market conditions for this resource as cattle feed.

Surveys of 39 rice straw stacks were conducted to define reasons for variability in forage quality.  Samples were tested for crude protein, acid detergent fiber (ADF) and moisture content.

Rice Straw manganese levels - 2002

Results of this study again illustrated that not all rice straw should be fed to cattle.  In 2001, UC Farm Advisor Glenn Nader developed guidelines for purchasing rice straw for feeding to cattle.  Laboratory test should establish a minimum 4.5 percent crude protein level and a maximum of 50 percent ADF.  Adherence to these guidelines will ensure that only the best forage quality product is used.

In 2002 only 25 percent of the samples met these guidelines and three samples should not have been fed to cows.  Protein levels from the 2002 samples were also lower, indicating the possibility of a year-effect on forage quality.

Work is also under way to better understand variations in Neutral Detergent Fiber (NDF), a measure of digestibility, that can be developed into field-level guidelines for selecting straw appropriate for cattle feeding and for standardized laboratory testing.

Variation in NDF content of rice straw samples

Another objective in this study was to define the impact of high levels of manganese in rice straw on cattle, a concern born out of previous years’ observations.  Eight of 21 samples contained more than 1,000 ppm, a level that is potentially toxic to cattle.  Limited research has indicated that high levels of manganese in feed can cause a decrease in an animal’s ability to absorb copper, which in turn can lead to a variety of physiological problems such as diarrhea and bone fractures.  In January 2003 scientists began a study at the UC Sierra Foothill Research and Extension Center to improve knowledge of the role of manganese in rice straw and its effect on cattle metabolism.  After 49 days of consuming a diet of 50 percent rice straw containing 1100 ppm manganese, no decrease in liver copper level occurred.

Publications or Reports

Feeding Rice Straw, an 18-page University of California publication developed by Nader and fellow UC Livestock Advisors Dan Drake and Larry Forero is available online at here